The majority of enclosures for electrical equipment, such as circuit breakers, panelboards or load centers, are formed of metal. These metallic enclosures are usually mass-produced from metal sheets in successive forming operations like cutting, blanking, and welding to make a box-like housing and cover. The enclosure is usually zinc-coated and painted. Various panels or other supports are assembled in the enclosure for mounting components or other elements for electrical distribution. Since the metallic enclosure is electrically conductive, insulators must be used for mounting the various bus bars within the enclosure.
In recent years, there has been significant utilization of plastic load center enclosures. For example, U.S. Pat. Nos. 4,909,551, 5,072,071 and 5,134,543, commonly assigned to the Square D Company, disclose a non-metallic, molded plastic, load center enclosure with a snap-fitted, circuit breaker bus bar support panel. Integrally formed with a side wall of the enclosure is a conductor mounting member with a v-shaped wire bending fixture to secure wires entering the load center. Since the entire enclosure is plastic and, thus, the conductor mounting member as well, there is no danger of shorting the wires.
There is a need to provide similar protection to the metallic enclosures. Wires usually enter a metallic enclosure through a "knock-out" which is a simple hole covered by a blank until it is punched out with a hammer and screwdriver or the like. The knock-out does not secure the wires to the enclosure wall. Multi-piece clamps must be assembled and attached to the wires for securing to the enclosure. These clamps are typically not provided by the manufacturer of the enclosure and also require wire clamping screws located on the exterior of the enclosure. Accordingly, a need exists to combine the advantages of an electrically-insulating wire management assembly with a metallic load center.